The invention relates to a hold-down apparatus for functional elements which are unfoldable from a carrying body such as a satellite carrying solar panels formed by such functional elements. A counter support on the carrying body supports the folded functional elements. A pressure piece is mounted on the functional element furthest away from the counter support. A pivotable retaining arm or bail is provided, one end of which may be set on the pressure piece for applying a downwardly directed force on the counter support.
Such an apparatus is known from European patent publication (EP-OS) 34,193 which discloses a hold-down apparatus for unfoldable panels carrying solar cells for spacecraft or satellites. During transportation into space the panels are folded-up and are braced or supported by a counter support attached to the spacecraft functioning as a carrying body. In order to be able to maintain this folded-up condition with certainty during flight, structural features are provided for the purpose of pressing the panels against the counter support with a high biasing force. For this purpose, the panel farthest away from the counter support carries a pressure piece onto which may be set a pivotable retaining arm or bail. The biasing force is then applied through tightening a clamp bolt which is connected to the retaining arm or bail and which is effective on the pressure piece. Further structural elements are provided in the known apparatus, for locking the retaining arm in this position, on the one hand, and for removing the locking at the desired moment, on the other hand. After a single unlocking, however, a new relocking is not possible. Rather, it is assumed that the panels, once unfolded, remain in this unfolded position.
Meanwhile, however, a stage has been reached in space technology in which repeatedly reusable components are used. Therefore, it may be rather desirable after a certain time to again fold-up and relock in this folded position functional elements which were once unfolded, such as panels carrying solar cells or even unfoldable antenna elements or the like.